JP 2014-110677 A discloses a driving assistance apparatus that performs a regeneration increasing control during a deceleration of a vehicle so that increased regenerated power can be acquired when stop position exists ahead of the vehicle at a turn-off time of an accelerator of the vehicle. The apparatus disclosed in JP 2014-110677 A includes a speed-distance map that stores a relationship between the most appropriate vehicle speed for starting the regeneration increasing control after the turn-off of the accelerator and a remaining distance to the stop position as an assistance execution line of the regeneration increasing control. The speed-distance map also includes an accelerator off allowable line and a regenerated power overflow line. The accelerator off allowable line indicates an allowable limit of the remaining distance at which the driver feels the turn-off of the accelerator is too early in a case where the driver has turned off the accelerator at a certain speed and moves toward the stop position with the regeneration increasing control being executed. The regenerated power overflow line indicates a limit of the remaining distance at which the overflow amount of the regenerated power does not exceed a predetermined value when the driver depresses the brake pedal after turning off the accelerator at a certain speed.
In JP 2014-110677 A, when the stop position is detected, an accelerator off position at which the accelerator should be turned off is calculated based on the speed of the vehicle by referring to the assistance execution line included in the speed-distance map. When the vehicle moves to a position, which is apart from the accelerator off position by a predetermined distance, before arriving at the accelerator off position, or when the current time is earlier than an estimated arrival time to the accelerator off position by a predetermined period, the driver is provided with the driving assistance information that instructs the turn-off of the accelerator. When the vehicle moves to the accelerator off position after turn off of the accelerator is notified to the driver or when the predetermined period has elapsed after the instruction for turning off of the accelerator is notified to the driver, the apparatus activates the regeneration increasing control. After the execution of the regeneration increasing control, a relationship between the vehicle speed and the remaining distance should be monitored for determining whether the relationship is included in the assistance execution region that is sandwiched between the accelerator off allowable line and the regenerated power overflow line. When the timely monitored relationship between the vehicle speed and the remaining distance is determined to go beyond of the assistance execution region, the apparatus stops or deactivates the regeneration increasing control.
In the apparatus disclosed in JP 2014-110677 A, the assistance execution line needs to be preliminarily defined and stored in the speed-distance map. Thus, when a slope of a road surface on which the vehicle travels is different from an assumed slope under which the assistance execution line is defined, a position for starting or activating the regeneration increasing control cannot be properly specified. Further, in this case, even when the regeneration increasing control is activated, the relationship between the vehicle speed and the remaining distance to the stop position easily exceeds from the assistance execution region. When the relationship between the vehicle speed and the remaining distance exceeds from the assistance execution region, the regeneration increasing control is deactivated. Thus, an increase in deactivation frequency of the regeneration increasing control may give an uncomfortable feeling to the driver.